diff --git a/README.md b/README.md
index 9df5f50..6e4f244 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ Features
 --------
 
 Supported operators: `!` `!=` `""` `''` `()` `[]` `,` `>` `<` `>=` `<=` `==`
-`+` `-` `*` `/` `%` `&&` `||` `n..m`.
+`+` unary/binary `-` `*` `/` `%` `&&` `||` `n..m`.
 
 Built-in functions: `min()` `max()` `len()` `is_empty()` `array()` `converge()`.
 See the `builtin` module for a detailed description of each.
diff --git a/src/lib.rs b/src/lib.rs
index ba35828..76433cb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,7 @@
 //! Eval is a powerful expression evaluator.
 //!
 //! Supported operators: `!` `!=` `""` `''` `()` `[]` `.` `,` `>` `<` `>=` `<=`
-//! `==` `+` `-` `*` `/` `%` `&&` `||` `n..m`.
+//! `==` `+` unary/binary `-` `*` `/` `%` `&&` `||` `n..m`.
 //!
 //! Built-in functions: `min()` `max()` `len()` `is_empty()` `array()` `converge()`.
 //!
@@ -111,6 +111,8 @@ mod error;
 mod builtin;
 mod expr;
 
+mod reboot;
+
 pub use expr::ExecOptions;
 pub use serde_json::Value;
 pub use error::Error;
@@ -604,6 +606,16 @@ mod tests {
         assert_eq!(eval("2 * (2 + 2) + (1 + 3)"), Ok(to_value(12)));
         assert_eq!(eval("2 * (4) + (4)"), Ok(to_value(12)));
     }
+
+    #[test]
+    fn test_unary_minus() {
+        assert_eq!(eval("3 + -4"), Ok(to_value(-1)));
+        assert_eq!(eval("3+-4"), Ok(to_value(-1)));
+        assert_eq!(eval("true && !false"), Ok(to_value(true)));
+        assert_eq!(eval("!true || !true"), Ok(to_value(false)));
+        assert_eq!(eval("-5 + -4"), Ok(to_value(-9)));
+        assert_eq!(eval("-3-4"), Ok(to_value(-7)));
+    }
 }
 
 #[cfg(all(feature = "unstable", test))]
diff --git a/src/operator/mod.rs b/src/operator/mod.rs
index d23423d..ed55a7f 100644
--- a/src/operator/mod.rs
+++ b/src/operator/mod.rs
@@ -8,6 +8,7 @@ use node::Node;
 
 #[derive(Debug, Clone, PartialEq)]
 pub enum Operator {
+    Neg(u8),
     Add(u8),
     Mul(u8),
     Sub(u8),
@@ -46,6 +47,7 @@ impl Operator {
 
     pub fn can_at_beginning(&self) -> bool {
         match *self {
+            Operator::Neg(_) |
             Operator::Not(_) |
             Operator::Function(_) |
             Operator::LeftParenthesis => true,
@@ -59,7 +61,7 @@ impl Operator {
             Operator::Eq(_) | Operator::Ne(_) | Operator::Gt(_) | Operator::Lt(_) |
             Operator::Ge(_) | Operator::Le(_) | Operator::And(_) | Operator::Or(_) |
             Operator::Rem(_) => Some(2),
-            Operator::Not(_) => Some(1),
+            Operator::Not(_) | Operator::Neg(_) => Some(1),
             Operator::Function(_) => None,
             _ => Some(0),
         }
@@ -71,7 +73,7 @@ impl Operator {
             Operator::Eq(_) | Operator::Ne(_) | Operator::Gt(_) | Operator::Lt(_) |
             Operator::Ge(_) | Operator::Le(_) | Operator::And(_) | Operator::Or(_) |
             Operator::Rem(_) => Some(2),
-            Operator::Not(_) => Some(1),
+            Operator::Not(_) | Operator::Neg(_) => Some(1),
             Operator::Function(_) => None,
             _ => Some(0),
         }
@@ -79,6 +81,7 @@ impl Operator {
 
     pub fn get_priority(&self) -> u8 {
         match *self {
+            Operator::Neg(priority) |
             Operator::Add(priority) |
             Operator::Sub(priority) |
             Operator::Div(priority) |
@@ -147,6 +150,7 @@ impl Operator {
             Operator::Or(_) |
             Operator::Ge(_) |
             Operator::Not(_) |
+            Operator::Neg(_) |
             Operator::Dot(_) |
             Operator::LeftSquareBracket(_) |
             Operator::Le(_) => true,
diff --git a/src/reboot/mod.rs b/src/reboot/mod.rs
new file mode 100644
index 0000000..e69de29